1 files changed, 150 insertions, 0 deletions
diff --git a/src/tutorial/C-code/complex.c b/src/tutorial/C-code/complex.c
new file mode 100644
index 00000000000..bebdd511d4d
--- /dev/null
+++ b/src/tutorial/C-code/complex.c
@@ -0,0 +1,150 @@
+#include <stdio.h>
+/* do not include libpq-fe.h for backend-loaded functions*/
+/* #include "libpq-fe.h"  */
+#include "postgres.h"
+#include "utils/elog.h"
+#include "utils/palloc.h"
+#include "utils/mcxt.h"
+
+typedef struct Complex {
+    double	x;
+    double	y;
+} Complex;
+
+/*****************************************************************************
+ * Input/Output functions
+ *****************************************************************************/
+
+Complex *
+complex_in(char *str)
+{
+    double x, y;
+    Complex *result;
+    
+    if (sscanf(str, " ( %lf , %lf )", &x, &y) != 2) {
+	elog(WARN, "complex_in: error in parsing \"%s\"", str);
+	return NULL;
+    }
+    result = (Complex *)palloc(sizeof(Complex));
+    result->x = x;
+    result->y = y;
+    return (result);
+}
+
+/*
+ * You might have noticed a slight inconsistency between the following
+ * declaration and the SQL definition:
+ *     CREATE FUNCTION complex_out(opaque) RETURNS opaque ...
+ * The reason is that the argument pass into complex_out is really just a
+ * pointer. POSTGRES thinks all output functions are:
+ *     char *out_func(char *);
+ */
+char *
+complex_out(Complex *complex)
+{
+    char *result;
+
+    if (complex == NULL)
+	return(NULL);
+
+    result = (char *) palloc(60);
+    sprintf(result, "(%lg,%lg)", complex->x, complex->y);
+    return(result);
+}
+
+/*****************************************************************************
+ * New Operators
+ *****************************************************************************/
+
+Complex *
+complex_add(Complex *a, Complex *b)
+{
+    Complex *result;
+    
+    result = (Complex *)palloc(sizeof(Complex));
+    result->x = a->x + b->x;
+    result->y = a->y + b->y;
+    return (result);
+}
+
+
+/*****************************************************************************
+ * Operator class for defining B-tree index
+ *****************************************************************************/
+
+#define Mag(c)	((c)->x*(c)->x + (c)->y*(c)->y)
+
+bool
+complex_abs_lt(Complex *a, Complex *b)
+{
+    double amag = Mag(a), bmag = Mag(b);
+    return (amag<bmag);
+}
+
+bool
+complex_abs_le(Complex *a, Complex *b)
+{
+    double amag = Mag(a), bmag = Mag(b);
+    return (amag<=bmag);
+}
+
+bool
+complex_abs_eq(Complex *a, Complex *b)
+{
+    double amag = Mag(a), bmag = Mag(b);
+    return (amag==bmag);
+}
+
+bool
+complex_abs_ge(Complex *a, Complex *b)
+{
+    double amag = Mag(a), bmag = Mag(b);
+    return (amag>=bmag);
+}
+
+bool
+complex_abs_gt(Complex *a, Complex *b)
+{
+    double amag = Mag(a), bmag = Mag(b);
+    return (amag>bmag);
+}
+
+int4
+complex_abs_cmp(Complex *a, Complex *b)
+{
+    double amag = Mag(a), bmag = Mag(b);
+    if (a < b)
+	return -1;
+    else if (a > b)
+	return 1;
+    else
+	return 0;
+}
+
+/*****************************************************************************
+ * test code
+ *****************************************************************************/
+
+/*
+ * You should always test your code separately. Trust me, using POSTGRES to
+ * debug your C function will be very painful and unproductive. In case of
+ * POSTGRES crashing, it is impossible to tell whether the bug is in your
+ * code or POSTGRES's.
+ */
+void
+test_main()
+{
+    Complex *a;
+    Complex *b;
+
+    a = complex_in("(4.01, 3.77 )");
+    printf("a = %s\n", complex_out(a));
+    b = complex_in("(1.0,2.0)");
+    printf("b = %s\n", complex_out(b));
+    printf("a +  b = %s\n", complex_out(complex_add(a,b)));
+    printf("a <  b = %d\n", complex_abs_lt(a,b));
+    printf("a <= b = %d\n", complex_abs_le(a,b));
+    printf("a =  b = %d\n", complex_abs_eq(a,b));
+    printf("a >= b = %d\n", complex_abs_ge(a,b));
+    printf("a >  b = %d\n", complex_abs_gt(a,b));
+}